How to Conduct a Machine Safety Assessment and Meet Industry Standards
Machine safety isn’t just about compliance. it’s about protecting human lives and ensuring reliable, efficient industrial operations. With the increasing integration of automated machinery in factories and processing plants, conducting a structured machine safety assessment is not only a legal obligation but a strategic necessity for minimizing downtime, reducing liability, and achieving long-term operational excellence.
This blog post outlines how to properly conduct a machine safety assessment based on international industry standards such as ISO 12100 and ISO 13849, with step-by-step guidance, real-world examples, and best practices.
Refer to the ANSI B11.0-2023 Safety Of Machinery :
ANSI B11.0-2023
What Is a Machine Safety Assessment?
A machine safety assessment is a structured process of identifying hazards, analyzing risks, and implementing safety controls to prevent injury or damage during machine operation. This assessment is guided by international safety standards and forms the foundation of a compliant Functional Safety Program.
Key Goals:
- Ensure worker and machine safety
- Achieve compliance with global safety regulations
- Define Performance Level (PL) or Safety Integrity Level (SIL)
- Guide the design or modification of safety control systems
Step 1: Define the Scope of Assessment
Start by identifying the machine or process to be evaluated.
Consider:
- Machine boundaries and interfaces
- Lifecycle stages (startup, operation, maintenance, decommissioning)
- People involved (operators, maintenance, contractors)
- Types of energy sources (electrical, hydraulic, pneumatic)
⚠️ Always involve a multidisciplinary team—including safety engineers, operators, electricians, and supervisors.
Step 2: Hazard Identification (ISO 12100)
ISO 12100:2010 is the foundational standard for general principles of machine safety.
Common Hazards:
| Hazard Type | Examples |
|---|---|
| Mechanical | Crushing, shearing, cutting, entanglement |
| Electrical | Shock, short circuit, arc flash |
| Thermal | Burns from hot surfaces, steam release |
| Noise & Vibration | Hearing damage, fatigue |
| Ergonomic | Awkward posture, repetitive motion |
Use checklists, diagrams, and observation techniques to list all potential hazards.
Step 3: Risk Assessment Using ISO 13849-1
ISO 13849-1:2015 provides a framework for analyzing and reducing risk using Performance Levels (PL).
Risk Parameters:
| Parameter | Description |
| S – Severity | Injury: Minor (S1), Severe (S2) |
| F – Frequency | Rare (F1), Frequent (F2) |
| P – Possibility | Possible to avoid (P1), Unlikely (P2) |
Based on these, determine the Required Performance Level (PLr):
| PL Rating | Risk Level |
| PLa | Low |
| PLb | Low to Medium |
| PLc | Medium |
| PLd | High |
| PLe | Very High |
Use tools like SISTEMA software to model safety functions and confirm that control circuits meet or exceed the PLr.
Step 4: Define Safety Functions
A safety function is a system action designed to prevent harm during hazardous events. It includes sensors, logic, and actuators.
Examples:
- Emergency stop (E-stop)
- Guard door monitoring
- Light curtain detection
- Safe speed monitoring
Each safety function must be:
- Defined clearly (trigger, logic, action)
- Matched to PLr
- Tested and validated
Step 5: Design and Implement Safety Measures
Select and install safety devices based on the required PLr.
Safety Components:
| Component | Function |
| Safety relay | Monitors E-stops, light curtains, doors |
| Safety PLC | Manages multiple safety functions |
| Contactors with feedback loop | Ensure safe power cutoff |
| Guard interlocks | Prevent access to hazardous zones |
Ensure your circuit follows redundancy, diagnostic coverage, and fail-safe principles.
Step 6: Verify and Validate the System
Validation confirms that the implemented safety measures function as intended under real conditions.
Checklist:
- Test all safety functions
- Simulate faults (e.g., disconnect sensors)
- Measure response times
- Verify proper reset behavior
- Document test procedures and results
This step ensures compliance with ISO 13849-2, which focuses on safety function validation.
Step 7: Documentation and Compliance Reporting
A thorough technical file or safety compliance dossier must be created. It is essential for:
- Audits
- Legal compliance
- Certification (e.g., CE marking)
Documentation Includes:
- Risk assessment matrix
- Block diagrams and circuit schematics
- PL calculations and justifications
- Safety function test protocols
- Manufacturer certifications
Industry Standards for Machine Safety
| Standard | Scope |
| ISO 12100 | General principles for risk assessment |
| ISO 13849-1/2 | Performance Level of safety systems |
| IEC 62061 | SIL-based functional safety |
| EN 60204-1 | Electrical equipment of machines |
| ANSI B11 Series | US standards for machine tools |
Always check local regulations (e.g., OSHA in the US, CE in the EU) for jurisdiction-specific rules.
Common Mistakes to Avoid
| Mistake | Solution |
| Relying only on PPE | Use engineering controls first |
| Incomplete hazard list | Use cross-functional review teams |
| Underestimating exposure | Observe multiple shifts or job tasks |
| Skipping validation | Simulate real faults before signoff |
| Poor documentation | Maintain traceable records for every step |
Real-World Example: Conveyor Safety Upgrade
Scenario: A packaging plant has a conveyor line with emergency stops and unguarded rollers.
Assessment:
- Mechanical entanglement risk: High severity, frequent exposure, hard to avoid (PLd)
- Added interlocked guards, dual-channel E-stops, and Pilz safety relay
- Verified using SISTEMA: Achieved PLd
Outcome: Zero safety incidents after upgrade and passed CE audit.
Best Practices for Effective Safety Assessments
- Start safety early—integrate during design, not post-installation.
- Standardize templates for assessment across the organization.
- Use digital tools (SISTEMA, Excel checklists, 3D hazard mapping)
- Train cross-functional teams on standards and methods.
- Review assessments periodically after changes or incidents.
Conclusion: Safety Is a System, Not a Feature
A successful machine safety assessment is the first priority of an effective and compliant industrial safety program. By following internationally accepted steps hazard identification, risk assessment, PL determination, function implementation, and validation you ensure not only compliance with ISO/IEC standards but also the creation of a culture of safety in your operations.
Don’t just meet the standard exceed it by designing safety into every level of your automation strategy